High specific intensity light source



June 14, 1966 w. s. MILLER 3,256,388

HIGH SPECIFIC INTENSITY LIGHT SOURCE Filed July 6, 1962 2 Sheets-Sheet 1 WENDELL S. M 11.1.5?

INVEN TOR.

ATTO ENEY June 14, 1966 w. s. MILLER 3,256,388

HIGH SPECIFIC INTENSITY LIGHT SOURCE Filed July 6, 1962 2 Sheets-Sheet 2 WENDELL S, MILL-E2 IN VEN TOR.

ATTORNEY United States Patent 3,256,388 HIGH SPECIFIC INTENSITY LIGHT SOURCE Wendell S.. Miller, 1341 Comstock Ave., Los Angeles, Calif. Filed July 6, 1962, Ser. No. 207,975 9. Claims. (Cl. 1787.88)

This invention relates to an improved type of light source, and particularly to a source capable of producing light at a very high intensity. The light may be used for any of numerous different purposes for which a bright light may be desired, one typical use being that of exposing slow photographic papers or film.

It is possible to produce an extremely bright spot of light on the face of a cathode ray tube, by directing an electron beam in the tube against a localized portion of the fluorescent or phosphorescentmaterial in the tube. However, this very bright light can be produced for only a very short period of time, preferably constituting a small fraction of a second, since extended bombarding of the fluorescent material with an electron beam will invariably burn out the fluorescent material. A major object of the present invention is to provide a bright light source which will overcome this disadvantage of cathode ray tubes as a source of intense illumination, and will enable a tube to produce a very bright light continuously without damage to the phosphors.

To attain this result, I cause the electron beam to sequentially impinge against and illuminate a series of different portions of the fluorescent material, and the light output from these various areas is then brought together in a manner such that the different light sources supplement one another and produce an overall beam which.

may be substantially continuous in operation. While one of the phosphors is illuminated, the others are resting and cooling, so that no single phosphor ever reaches a burn out temperature.

Preferably, the light outputs from the various fluorescent areas are formed into individual beams, which beams may be so directed as to converge toward one another, and desirably toward a single point spaced from the face of the cathode ray tube. formed by individual light directing units, which may consist of reflectors acting to form the light from each of the fluorescent areas into a pencil or bundle of generally parallel rays. Also, the light directing units may include lenses acting to further control the formation and directing of the light beams.

The light directing apparatus preferably includes means acting to direct the different beams from the various fluorescent areas toward positions of closer alignment with one another. In the optimum arrangement, all of the various individual beams are substantially exactly aligned with one another, and are spacially co-extensive in every respect, that is their chief rays coincide and their cross- .sectional areas and light distribution patterns are the same,

so that there is substantially no variation in the intensity While the invention is discussed primarily herein as applied to cathode ray tubes, it is contemplated broadly that some of the advantages of the invention may be attained in arrangements in which other types of self luminous screen's, such as electroluminescent screens, are employed.

The above and other features and objects of the present invention will be better understood from the following detailed description of the typical embodiments illustrated in the accompanying drawings, in which:

FIG.- 1 is a vertical section through a light source arrangement constructed in accordance with the invention;

FIG. 2 is a plan view of the FIG. 1 apparatus;

FIG. 3 is a greatly enlarged fragmentary generally vertical section through a portion of the face of the cathode ray tube of FIG. 1 taken essentially on line 33 of FIG. 1;

FIG. 4 is an enlarged partially diagrammatic section taken on line 44 of FIG. 1; and

FIG. 5 is a view similar to FIG. 3, but showing a variational type of light producing face on the cathode ray tube.

Referring first to FIG. 1, I have shown at 10 a cathode ray tube having a transverse end face 11 which is adapted to be illuminated by impingement on that face of an electron beam 12 from an electron gun 13. The electron beam is produced by the maintenance of -a very high difference in electrical potential between the cathode 14 and an anode at the illuminated end of the tube. It is contemplated that this anode may be a conventional anode as represented at 15, or the-face 11 may itself serve as the anode, or both of the elements 11 and 15 may serve together as the anode of the tube, and be connected to the positive side 16 of high voltage power source 17.

Beam 12 is caused to scan face 11 both horizontally and vertically by the application of appropriate scanning The different beams may be of the light beam in shifting from one phosphor area to another. I

T 0 bring the light beams into alignment or coincidence with one another, I may utilize scanning means acting to compensate for the spacing between different ones of the fluorescent areas on the cathode ray tube. These scanning means may include a mirror moving in correspondbe a multiple face rotating mirror structure.

.signals to vertical deflection coils 117 and horizontal deflection coils 18, these signals being supplied by vertical and horizontal signal generators 19 and 20. The current flowing through coils 1 17 and 18 from generators 19 and '20 may be such as to cause the electron beam to scan across the rear side of face 11 in a predetermined number of horizontal lines, and to then return to the top of face 11 to repeat the process after the bottom line has been completed. The signal from horizontal deflection signal generator 20 may if desired be a rapid return fly-back type of signal, as in conventional television sets, or, as assumed in the present drawing, may be a sine wave signal, causing the electron beam to scan the tube in both directions horizontally along the zigzag path represented at 70 in FIG. 4.

The structure of the screen or face 11 will be best understood by reference to FIGS. 1, 3 and 4. Screen 11 includes a main body or plate 19' which may be formed of metal and which may have the generally rectangular cross-section illustrated in FIG. 4, to extend across the entire front end of tube 10. At its periphery, plate 19' may be connected to a bellows 120, which is in turn cemented orotherwise tightly secured to the front edge portion of the glass wall 21 of tube 10, in a relation forming an air-tight seal acting to maintain the desired vacuum condition within tube 10. Bellows 120 is of course sufliciently strong to withstand the pressure differential resulting from this vacuum condition, and for this purpose may be formed of a rather strong metal.

When the screen 11 itself is to serve as the anode, or a portion of the anode, the plate 19' is rendered electrically conductive, as by forming it of copper or the like, and is connected electrically to anode lead 16. Also, plate 19' may be of a highly heat conductive material, so that it may assist in carrying off excess heat developed in the illumination process. Copper of course is also 3 I very desirable for this heat conductive purpose. To carry the heat away from plate 19', there may be formed in this plate a series of passages 22, closed at their rear sides by a cover or rear plate 23, for conducting a cooling fluid through screen 11. Cover 23 may also be formed of copper or other suitable highly seat conductive and electrically conductive material, and may be welded, cemented, or otherwise securely bonded to plate 19', to maintain the integrity of passages 22. The passages 22 may extend generally horizontally from one side of screen 11 to the other, and be connected at a first side of the screen to a cooling fluid inlet header 24 (FIG. 4), and be connected at the opposite side to a cooling fluid outlet header 25. The fluid is forced through the system by a pump 26, taking suction from a reservoir 27, to which the fluid returns from header 25 after passing through a cooler 28. Headers 24 and 25 may be connected to the various fluid passages 22 in the screen by means of small connector tubes 29.

The plates 19' and 23 contain several near horizontal rows R-l, R2, R-3 etc. (FIG. 4) of apertures 30 which are shaped to serve as small reflectors acting to direct individual light beams to the left as viewed in FIGS. 1 and 2. Each of these apertures 30 has a relatively large diameter essentially circular light discharge end 31, and a much smaller generally circular light inlet end 32. A small spot of phosphorescent material 33 is disposed across the small end 32 of each reflector passage 30, and acts when bombarded by electron beam 12 to produce light in the associated reflector. The reflectors are desirably of parabolic axial section (see FIG. 3), and have a highly reflective substance coating their inner parabolic surfaces 34 to specularly reflect light emitted from phosphor 33, and thereby produce individual bundles or pencils of light rays from the different reflectors 30 respectively. For example, the particular reflector designated 30 in FIG. 3 acts to produce a bundle of approximately parallel light rays centered about an axis or chief ray 35, and falling within the circular cross-section defined by the lines 36 in FIG. 3. The reflective material coating surfaces 34 may be aluminum, silver, or the like, and is represented at 37 in FIG. 3.

The formation of the light rays from the different reflectors 30 into individual light beams or bundles of rays may be assisted by positioning lenses 38 in front of the discharge ends of the various reflectors. For simplicity of manufacture, these lenses 38 may be all formed of a single piece of molded glass, having the illustrated convex forward lens surfaces acting to assist in preventing divergence of the light rays from the reflectors. The glass plate forming lenses 38 may have integral lugs or projections 39 at its rear side, projecting into and fitting closely within the various reflectors, and carrying the phosphorescent material 33 at the extremities of the lugs. The glass forming plate 3839 is preferably completely transparent and clear, and may be bonded to the walls 34 of the reflectors by a clear cement capable of forming an effective fluid-tight joint between the glass and the copper of plates 19 and 23 without interfering with the internal reflection within the reflector units. The lens 38 associated with each of the parabolic reflectors 30 is of course centered about the axis of that reflector.

It may be assumed that the reflector designated 30' in FIG. 3 is the center reflector of the entire screen or face plate 11. The axis 35 along which the chief ray of the beam produced by reflector 30' advances may therefore be directly perpendicular to the planes 40 and 41 of the front and rear surfaces of plates 19 and 23. The reflector just above reflector 30' is directed slightly downwardly, so that the beam produced by this reflector follows a downwardly inclined axis 42. The next higher reflector directs its beam downwardly at an even greater angle, and simi larly the still higher reflectors direct their beams at progressively increasing angles so that the uppermost reflector has an axis 44 of rather great inclination. In the same way, the reflectors beneath central reflector 30, or to the left or right of that reflector are all disposed at angles which progressively increase as the distance from axis 35 increases. The angularity of all the different reflectors 30 is such as to cause all of the beams to focus on a particular predetermined spot 45 spaced from screen 11. A conical reflector 46, having an internally aluminized or reflectorized surface 47, may be disposed about the path of the converging light beams from the different reflectors, to prevent the loss of any stray light from the individual light sources, and assure the ultimate arrival of substantially all of the light energy at the discharge end of cone 46.

The scanning pattern of electron beam 12 is controlled to cause the-beam to first scan horizontally along and illuminate the upper row of phosphors 33, then scan in the opposite horizontal direction across and sequentially illuminate the second row of phosphors, following which the third row of phosphors are scanned in the first direction, etc.

The converging light beams from the various reflectors 30 are directed by the reflector structure along converging paths and toward a common point 45, but of course are not aligned axially with one another when they reach that point. In order to bring the beams into such alignment or spacial coincidence, I provide a scanning system acting to compensate for or counteract the scanning'motion of the electron beam 12. This counteracting scanning system may include two mirrors 48 and 49, acting to compensate for the horizontal and vertical scanning motion respectively of the electron beam.- Mirror 48 is a planar specularly reflective element, mounted to rotatably oscillate about an inclined axis 50, and functioning to direct the light beams from screen 11 upwardly as indicated by the line 51 in FIG. 1. At its upper side, mirror 48 may carry a shaft 52, which is journaled within a bearing 53 for rotary oscillating movement about axis 50. The lower side of mirror 48 may be connected to one end of a piezo electric crystal 54, which is rigidly connected at its opposite end to a stationary frame member 55, and which is constructed and mounted to operate in a torsion mode, to turn mirror 48 about axis 50 in accordance with the application of electrical energy to crystal 54. The crystal is energized by a sine wave input signal in timed relation to the energization of horizontal deflection coils 18 of the cathode ray tube, as by providing a timer 56 receiving and responding to a signal from the leads leading to coils 18, with the timer then controlling the power source 57 which supplies actuating energy to piezo electric crystal 54. As will be apparent, mirror 48 is turned just sufliciently to always compensate for the extent to which a particular illuminated phosphor is offset laterally from the vertical central plane in which main axis 35 of the apparatus lies, so that the light rays reflected upwardly at 51 by mirror 48 always lie in a common vertical plane, regardless of which reflector 30 may have been the source of the particular beam being reflected at a certain instant. However, mirror 48 does not compensate for the vertical displacement of any particular reflector 30 from axis 35. To compensate for this vertical scanning of the electron beam, the mirror assembly 49 is shaped to have a number of preferably identical and preferably evenly circularly spaced radially outwardly facing specularly reflective mirror faces 57, each of which may be planar. As an example, the mirror assembly 49 may present thirty-two such mirror faces. This assembly turns about an axis 58 which may extend generally parallel to the horizontal lines which are scanned by electron beam 12. The mirror assembly 49 is driven about this axis by a motor 59, through a timing chain or other drive mechanism typically represented at 60. The rotation of mirror 49 and its motor 59 are timed to the vertical scanning movement of electron beam 12, and for this purpose the power source 61 which drives motor 59 may be controlled by a timer 62 which is in turn controlled by the pulses fed to vertical deflection coils 117 by the vertical signal generator 19. Preferably, the motor 59 is a synchronous motor to assure accurate timing of the rotation of mirror 49. The rate of rotation of mirror 49 is such as to exactly compensate for the vertical movement of electron beam 12, and thereby cause all-of the various individual light beams from the different reflectors 30 to be exactly aligned with one another and -centered about a common axis 63 as they emit from mirror 49. Also, the positioning and rate of rotation of mirror 49 are such that, during each complete scan of the entire face of screen 11, all of the individual light beams produced by that scan will be reflected by a single predetermined one of the mirror faces 57 of assembly 49. At the completion of that full scan, after the bottom row has been completed by electron beam 12, the beam returns upwardly to a top row, and at the same time the mirror faces 57 reach a point such that the light beams produced by the next scan will be reflected by the next successive mirror face 57.

It will be apparent from the above discussion that, when the apparatus of FIGS. 1 through 4 is in operation, the electron beam acts to first sequentially energize and illuminate the various reflectors 30 of top row R then scan the second row, etc. At any particular instant, only one of the phosphors is energized by the electron beam, and therefore only one reflector 30 produces a light beam directed toward 45. At that particular instant, the positioning of mirror 48 compensates for the extent to which the particnlar'phosphor in question is offset laterally from the vertical plane of main axis 35, and similarly the positioning of mirror 49 compensates for the vertical offset of the phosphor and its reflector from axis 35, so that the overall result is to cause the particular light beam produced to emit from the apparatus in exact alignment with axis 63. By the time that the next succesisve phosphor is energized, the mirrors have 'moved to a position to compensate for the vertical and horizontal offset of that particular phosphor from axis 35, so that the light beam produced by that phosphor also is aligned with axis 63. This continues throughout the entire scanning operation, and as a result the light beams all coincide with one another and with axis 63, to produce a continuous high intensity beam along that axis. In order to assure optimum alignment, it is preferred that the phosphors may be of very low persistence, so that no two phosphors will be 1llum1- ,nated, at least to their maximum intensity, at the same time.

FIG. 5 is a view similar to FIG; 3, but showing a slightly variational form of the invention. In this FIG. 5 arrangement, the glass lugs 39a have beads or projections 64 projecting through and beyond apertures 32a in rear plate 23a, with a continuous layer 33a of phosphorescent material being painted on the back side of plate 23a, in place of the small spots 33 of such material in FIG. 3. The electron beam then scans across the rear side of phosphorescent material 33a, along the different rows of reflectors 30a, with the result that when the electron beam is directly behind one of the glass beads 64, the phosphorescent material surrounding that bead is illuminated, to correspondingly illuminate the bead. More particularly, the space defined by each of the beads 64 functions as a radiation cavity, acting to cause the emission through aperture 32a of a maximum intensity of radiation at the frequency at which phosphorescent material 33a fluoresces. Thus, the arrangement of FIG. 5 acts under certain circumstances to increase the brightness of the light produced by the assembly.

If a conventional fly-b'ack type of horizontal scanning signal is supplied by generator 20, instead of the above discussed sine wave signal, the horizontal scanning rows R R R etc. of FIG. 4 then become parallel to one another, and it is desirable in such a case to substitute for oscillating mirror 48 a rotating mirror type of scanning mechanism corresponding to that shown at 49.

Iclaim:

1. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for directing an electron beam against said areas sequentially to excite them to lighted condition, means forming the light from said different areas of said electron excited luminous material into a plurality of different light beams respectively extending in different directions, and means for then directing said different beams toward paths of closer alignment with one another.

2. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for directing an electron beam against said areas sequentially to excite them to lighted condition, means forming the light from said different areas of said electron excited luminous material into a plurality of difierent light beams respectively which converge toward one another, and means for then directing said different beams toward paths of closer alignment with one another.

3. The combination comprising a cathode ray tube having a face carrying a plurality of diiferent areas of luminous materialexcitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for directing an electron beam against said areas sequentially to excite them to lighted condition, individual light directing units for said different areas including individual reflectors forming the light from said different areas of said electron excited luminous material into a plurality of individual beams respectively each consisting of a bundle of generally parallel light rays, and a structure of heat conductive material having portions disposed about and between said reflectors.

4. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for directing an electron beam against said areas sequentially to excite them to lighted condition, individual light directing units for said different areas including individual reflectors forming the light from said different areas of said electron excited luminous material into a plurality of individual beams respectively each consisting of -a bundle of generally parallel light rays, and a structure of electrically conductive material having portions disposed about and between said reflectors.

5. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for directing an electron beam against said areas sequentially to excite them to lighted condition, individual light directing units for said different areas including individual reflectors forming the light from said different areas. of said electron excited luminous material into a plurality of individual beams respectively each consisting of a bundle of generally parallel light rays, said reflectors having reduced dimension light inlet ends and larger light discharge ends, and means fonming radiation cavities in said luminous material at said inlet ends of the reflectors.

6. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for producing an electron beam and for moving said beam to impinge against said different areas in a predetermined sequence to illuminate them sequentially, and scanning means operable to receive light extending in different directions from said differentareas of said electron excited material and to direct it in generally a predetermined direction and including light directing means and means for shifting said light directing means essentially in timed relation to the movement of said electron beam and in a relation at least partially compensating for the differences in the positions of said luminous areas to direct the light from said different areas in generally said predetermined direction.

7. The combination comprising a cathode ray tube having a face carrying a plurality of different areas of luminous material excitable to an illuminated condition by impingement of an electron beam on said material, said tube including means for producing an electron beam and for moving said beam to impinge against said areas sequentially to illuminate them, means forming the light from said different areas of said electron excited material into a plurality of individual beams respectively which converge toward one another, and scanning means in the path of said converging beams and operable to direct said lbeams toward alignment with one another and including two power actuated mirrors shifting in essentially timed relation to the operation of said electron beam and in essentially two mutually perpendicular directions respectively to compensate for the differences in the directions in Which said converging light beams extend and brin them more into alignment. 7

8-. The combination comprising a luminous screen carrying a plurality of different areas of luminous material 8 excitable to lighted condition, means for sequentially exciting said areas to said lighted condition, means forming the light from said different areas intoa plurality of different light beams respectively which converge toward one another, and means for then directing said different beams toward paths of closer alignment with one another. 9. The combination comprising a luminous screen carrying a plurality of different areas of luminous material excitable to lighted condition, means for sequentially exciting said areas to said lighted condition, light directing means for forming light from said areas into different light beams converging toward one another, said light directing means including individual reflectors for said different areas, and lenses coacting with said reflectors to assist in forming said beams.

References Cited by the Examiner UNITED STATES PATENTS 2,934,653 4/1960 Hulst 250 217 3,027,219 3/1962 Bradley 34s 1'10 3,170,066 2/1965 Ogland 2s0 199 FOREIGN PATENTS 819,361 7/1937 France.

DAVID G. REDINBAUGH, Primary Examiner.

J. A. OBRIEN, Assistant Examiner. 

1. THE COMBINATION COMPRISING A CATHODE RAY TUBE HAVING A FACE CARRYING A PLURALITY OF DIFFERENT AREAS OF LUMINOUS MATERIAL EXCITABLE TO AN ILLUMINATED CONDITION BY IMPINGEMENT OF AN ELECTRON BEAM ON SAID MATERIAL, SAID TUBE INCLUDING MEANS FOR DIRECTING AN ELECTRON BEAM AGAINST SAID AREAS SEQUENTIALLY TO EXCITE THEM TO LIGHTED CONDITION, MEANS FORMING THE LIGHT FROM SAID DIFFERENT AREAS OF SAID ELECTRON EXCITED LUMINOUS MATERIAL INTO A PLURALITY OF DIFFERENT LIGHT BEAMS RESPECTIVELY EXTENDING IN DIFFERENT DIRECTIONS, AND MEANS FOR THEN DIRECTIG SAID DIFFERENT BEAMS TOWARD PATHS OF CLOSER ALIGNMENT WITH ONE ANOTHER. 